Link establishment in a wireless backhaul network using radio access technology

ABSTRACT

A solution to enable synchronization and establishing links among the APs using available RATs with minimum modifications is provided. In one aspect, an apparatus may determine a first set of resources to be used for establishing network access for a set of UEs. The apparatus may determine a second set of resources for establishing backhaul links with a set of base stations. A resource schedule of the apparatus may include the first set of resources and the second set of resources. In another aspect, an apparatus may be a first base station. The first base station may receive a set of reports from a set of base stations. The first base station may determine a resource schedule for a second base station within the set of base stations based on the set of reports. The first base station may transmit the resource schedule to the second base station.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Divisional of U.S. patent application Ser. No.15/392,911, entitled “LINK ESTABLISHMENT IN A WIRELESS BACKHAUL NETWORKUSING RADIO ACCESS TECHNOLOGY” and filed Dec.28, 2016, which claims thebenefit of U.S. Provisional Application Ser. No. 62/373,743, entitled“LINK ESTABLISHMENT IN A WIRELESS BACKHAUL NETWORK USING RADIO ACCESSTECHNOLOGY” and filed on Aug. 11, 2016, which is expressly incorporatedby reference herein in its entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to a wireless backhaul network.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis Long Term Evolution (LTE). LTE is a set of enhancements to theUniversal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). LTE isdesigned to support mobile broadband access through improved spectralefficiency, lowered costs, and improved services using OFDMA on thedownlink, SC-FDMA on the uplink, and multiple-input multiple-output(MIMO) antenna technology. However, as the demand for mobile broadbandaccess continues to increase, there exists a need for furtherimprovements in LTE technology. These improvements may also beapplicable to other multi-access technologies and the telecommunicationstandards that employ these technologies.

A hierarchical telecommunications network may have a hierarchical cellstructure in which a larger cell (e.g., a macro cell) may be rearrangedto include small cells (e.g., micro cells or pico cells). A micro/picocell is allocated the radio spectrum to serve the increased population.In a hierarchical telecommunications network, the backhaul portion ofthe network includes the intermediate links between the core network, orbackbone network and the small subnetworks at the “edge” of the entirehierarchical network. Reducing the cost of the backhaul network andincreasing the flexibility of the backhaul network may be desirable.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Using cellular radio access technologies (RATs) such as millimeter wave(mmW) for backhauling purposes may allow access points (APs) toself-backhaul access traffic to a suitable high-capacity fiber point andpermit resource-efficient spectrum utilization. In this disclosure, asolution to enable synchronization and establishing links among the APsusing available RATs with minimum modifications is provided.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus for wireless communication are provided. The apparatusmay be a base station. The apparatus may determine a first set ofresources to be used for establishing network access for a set of UEs.The apparatus may determine a second set of resources for establishingbackhaul links with a set of base stations. A resource schedule of theapparatus may include the first set of resources and the second set ofresources.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus for wireless communication are provided. Theapparatus may be a first base station. The first base station mayreceive a set of reports from a set of base stations. The first basestation may determine a resource schedule for a second base stationwithin the set of base stations based on the set of reports. The firstbase station may transmit the resource schedule to the second basestation.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating LTE examples of a DLframe structure, DL channels within the DL frame structure, an UL framestructure, and UL channels within the UL frame structure, respectively.

FIG. 3 is a diagram illustrating an example of an evolved Node B (eNB)and user equipment (UE) in an access network.

FIG. 4A shows an example of a wireless access network which supportsaccess to UEs.

FIG. 4B shows another example of a wireless access network whichsupports access to UEs.

FIG. 4C illustrates an example of narrow pencil beams being used foraccess links and backhaul links.

FIG. 5 is a diagram illustrating an example of resource allocation in ammW system.

FIG. 6 is a diagram illustrating an example of using a color-code todetermine when to switching from transmitting to listening tosynchronization signals for each AP.

FIG. 7 is a flowchart of a method of wireless communication.

FIG. 8 is a flowchart of a method of wireless communication.

FIG. 9 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, and an Evolved Packet Core (EPC) 160. The basestations 102 may include macro cells (high power cellular base station)and/or small cells (low power cellular base station). The macro cellsinclude eNBs. The small cells include femtocells, picocells, andmicrocells.

The base stations 102 (collectively referred to as Evolved UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)) interface with the EPC 160 through backhaul links 132 (e.g.,S1 interface). In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160) with eachother over backhaul links 134 (e.g., X2 interface). The backhaul links134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use MIMO antennatechnology, including spatial multiplexing, beamforming, and/or transmitdiversity. The communication links may be through one or more carriers.The base stations 102/UEs 104 may use spectrum up to Y MHz (e.g., 5, 10,15, 20 MHz) bandwidth per carrier allocated in a carrier aggregation ofup to a total of Yx MHz (x component carriers) used for transmission ineach direction. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or less carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ LTE and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing LTE in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network. LTE in an unlicensedspectrum may be referred to as LTE-unlicensed (LTE-U), licensed assistedaccess (LAA), or MuLTEfire.

The millimeter wave (mmW) base station 180 may operate in mmWfrequencies and/or near mmW frequencies. Extremely high frequency (EHF)is part of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 184 tocompensate for the extremely high path loss and short range.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService (PSS), and/or other IP services. The BM-SC 170 may providefunctions for MBMS user service provisioning and delivery. The BM-SC 170may serve as an entry point for content provider MBMS transmission, maybe used to authorize and initiate MBMS Bearer Services within a publicland mobile network (PLMN), and may be used to schedule MBMStransmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The base station may also be referred to as a Node B, evolved Node B(eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), or some other suitableterminology. The base station 102 provides an access point to the EPC160 for a UE 104. Examples of UEs 104 include a cellular phone, a smartphone, a session initiation protocol (SIP) phone, a laptop, a personaldigital assistant (PDA), a satellite radio, a global positioning system,a multimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a smart device, a wearabledevice, or any other similar functioning device. The UE 104 may also bereferred to as a station, a mobile station, a subscriber station, amobile unit, a subscriber unit, a wireless unit, a remote unit, a mobiledevice, a wireless device, a wireless communications device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology.

Referring again to FIG. 1 , in certain aspects, the mmW base station 180may be configured to establish (198) link in a wireless backhaul networkusing radio access technology. The operations performed at 198 will bedescribed below in detail with reference to FIGS. 2-10 .

FIG. 2A is a diagram 200 illustrating an example of a DL frame structurein LTE. FIG. 2B is a diagram 230 illustrating an example of channelswithin the DL frame structure in LTE. FIG. 2C is a diagram 250illustrating an example of an UL frame structure in LTE. FIG. 2D is adiagram 280 illustrating an example of channels within the UL framestructure in LTE. Other wireless communication technologies may have adifferent frame structure and/or different channels. In LTE, a frame (10ms) may be divided into 10 equally sized subframes. Each subframe mayinclude two consecutive time slots. A resource grid may be used torepresent the two time slots, each time slot including one or more timeconcurrent resource blocks (RBs) (also referred to as physical RBs(PRBs)). The resource grid is divided into multiple resource elements(REs). In LTE, for a normal cyclic prefix, an RB contains 12 consecutivesubcarriers in the frequency domain and 7 consecutive symbols (for DL,OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a totalof 84 REs. For an extended cyclic prefix, an RB contains 12 consecutivesubcarriers in the frequency domain and 6 consecutive symbols in thetime domain, for a total of 72 REs. The number of bits carried by eachRE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry DL reference (pilot)signals (DL-RS) for channel estimation at the UE. The DL-RS may includecell-specific reference signals (CRS) (also sometimes called common RS),UE-specific reference signals (UE-RS), and channel state informationreference signals (CSI-RS). FIG. 2A illustrates CRS for antenna ports 0,1, 2, and 3 (indicated as R₀, R₁, R₂, and R₃, respectively), UE-RS forantenna port 5 (indicated as R₅), and CSI-RS for antenna port 15(indicated as R). FIG. 2B illustrates an example of various channelswithin a DL subframe of a frame. The physical control format indicatorchannel (PCFICH) is within symbol 0 of slot 0, and carries a controlformat indicator (CFI) that indicates whether the physical downlinkcontrol channel (PDCCH) occupies 1, 2, or 3 symbols (FIG. 2B illustratesa PDCCH that occupies 3 symbols). The PDCCH carries downlink controlinformation (DCI) within one or more control channel elements (CCEs),each CCE including nine RE groups (REGs), each REG including fourconsecutive REs in an OFDM symbol. A UE may be configured with aUE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCHmay have 2, 4, or 8 RB pairs (FIG. 2B shows two RB pairs, each subsetincluding one RB pair). The physical hybrid automatic repeat request(ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0and carries the HARQ indicator (HI) that indicates HARQ acknowledgement(ACK)/negative ACK (NACK) feedback based on the physical uplink sharedchannel (PUSCH). The primary synchronization channel (PSCH) is withinsymbol 6 of slot 0 within subframes 0 and 5 of a frame, and carries aprimary synchronization signal (PSS) that is used by a UE to determinesubframe timing and a physical layer identity. The secondarysynchronization channel (SSCH) is within symbol 5 of slot 0 withinsubframes 0 and 5 of a frame, and carries a secondary synchronizationsignal (SSS) that is used by a UE to determine a physical layer cellidentity group number. Based on the physical layer identity and thephysical layer cell identity group number, the UE can determine aphysical cell identifier (PCI). Based on the PCI, the UE can determinethe locations of the aforementioned DL-RS. The physical broadcastchannel (PBCH) is within symbols 0, 1, 2, 3 of slot 1 of subframe 0 of aframe, and carries a master information block (MIB). The MIB provides anumber of RBs in the DL system bandwidth, a PHICH configuration, and asystem frame number (SFN). The physical downlink shared channel (PDSCH)carries user data, broadcast system information not transmitted throughthe PBCH such as system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry demodulation referencesignals (DM-RS) for channel estimation at the eNB. The UE mayadditionally transmit sounding reference signals (SRS) in the lastsymbol of a subframe. The SRS may have a comb structure, and a UE maytransmit SRS on one of the combs. The SRS may be used by an eNB forchannel quality estimation to enable frequency-dependent scheduling onthe UL. FIG. 2D illustrates an example of various channels within an ULsubframe of a frame. A physical random access channel (PRACH) may bewithin one or more subframes within a frame based on the PRACHconfiguration. The PRACH may include six consecutive RB pairs within asubframe. The PRACH allows the UE to perform initial system access andachieve UL synchronization. A physical uplink control channel (PUCCH)may be located on edges of the UL system bandwidth. The PUCCH carriesuplink control information (UCI), such as scheduling requests, a channelquality indicator (CQI), a precoding matrix indicator (PMI), a rankindicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, andmay additionally be used to carry a buffer status report (BSR), a powerheadroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of an eNB 310 in communication with a UE 350in an access network. In the DL, IP packets from the EPC 160 may beprovided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a packet dataconvergence protocol (PDCP) layer, a radio link control (RLC) layer, anda medium access control (MAC) layer. The controller/processor 375provides RRC layer functionality associated with broadcasting of systeminformation (e.g., MIB, SIBs), RRC connection control (e.g., RRCconnection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter radio access technology(RAT) mobility, and measurement configuration for UE measurementreporting; PDCP layer functionality associated with headercompression/decompression, security (ciphering, deciphering, integrityprotection, integrity verification), and handover support functions; RLClayer functionality associated with the transfer of upper layer packetdata units (PDUs), error correction through ARQ, concatenation,segmentation, and reassembly of RLC service data units (SDUs),re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto transport blocks(TBs), demultiplexing of MAC SDUs from TBs, scheduling informationreporting, error correction through HARQ, priority handling, and logicalchannel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe eNB 310. These soft decisions may be based on channel estimatescomputed by the channel estimator 358. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 310 on the physical channel. Thedata and control signals are then provided to the controller/processor359, which implements layer 3 and layer 2 functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the eNB 310, the controller/processor 359 provides RRClayer functionality associated with system information (e.g., MIB, SIBS)acquisition, RRC connections, and measurement reporting; PDCP layerfunctionality associated with header compression/decompression, andsecurity (ciphering, deciphering, integrity protection, integrityverification); RLC layer functionality associated with the transfer ofupper layer PDUs, error correction through ARQ, concatenation,segmentation, and reassembly of RLC SDUs, re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the eNB 310 may be used by the TXprocessor 368 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 368 may be provided to different antenna 352 viaseparate transmitters 354TX. Each transmitter 354TX may modulate an RFcarrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 310 in a manner similar tothat described in connection with the receiver function at the UE 350.Each receiver 318RX receives a signal through its respective antenna320. Each receiver 318RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Cellular technologies such as mmW may be used to support access trafficbetween UE and AP as well as for backhauling of access traffic amongAPs. It may be further possible that access and backhauling share thesame resources, which may be referred to as an IntegratedAccess/Backhaul (IAB) solution. The sharing of the same wireless channelby both the access traffic and the backhauling of access traffic may bereferred to as self-backhauling.

Such self-backhauling or IAB solutions may be promising with theevolution of cellular technologies due to the enhancements in wirelesslink capacity and reduction in latency. Further, self-backhauling mayreduce the cost of dense small cells deployments.

FIG. 4A shows an example of a wireless access network which supportsaccess to UEs. In this example, each AP (e.g., the AP 402, 404, 406,408, or 410) may be connected/coupled to a fiber point (e.g., the fiberpoint 412, 413, 414, 415, 416, respectively) to backhaul access trafficvia the fiber point. Thus, there may be one fiber point per AP and theremay be no wireless backhaul network between the APs.

FIG. 4B shows another example of a wireless access network whichsupports access to UEs. In this example, one fiber point 420 isprovisioned. For example, the AP 422 may be connected directly to thefiber point 420 to backhaul access traffic, while access traffic of APs424, 426, 428, and 430 may be exchanged with the fiber point 420 via awireless backhaul network established among the APs (e.g., APs 422, 424,426, 428, and 430).

Self-backhauling may be especially promising when using mmW-based radiotechnologies which apply very narrow antenna beams to reduce inter-linkinterference. Further, dynamic beam-steering and beam-searchcapabilities may be used to support discovery, link establishment andrefinement in the presence of dynamic shadowing and Rayleigh fading.

FIG. 4C illustrates an example of narrow pencil beams being used foraccess links and backhaul links. In this example, one fiber point 450 isprovisioned. For example, the AP 452 may be connected/coupled directlyto the fiber point 450 to backhaul access traffic via the fiber point450 (e.g., to the core network or backbone network), while accesstraffic of APs 454, 456, 458, and 460 may be exchanged with the fiberpoint 450 via a wireless backhaul network established among the APs(e.g., the APs 452, 454, 456, 458, and 460). Since APs may have largerantenna arrays compared to the UEs, the pencil beams of the APs may benarrower.

One of the main challenges of creating the wireless backhaul network forcarrying access traffic of APs without a fiber point and coordinatingthe resources among the APs may be the half-duplexing constraint, i.e.,an AP cannot receive and transmit at the same time in the same frequencyband. Coordinating timing of transmission and reception may be possiblevia time synchronizing all links and imposing a frame structure as it issupported by cellular RATs.

In cellular RATs, a UE may establish a link to an AP by performingsynchronization to align the UE's time and frequency with the AP andacquire system and AP information. To establish a link to an AP, the UEmay further transmit a random access channel (RACH) preamble to the APto inform the AP about the UE's presence and request resources forfurther communications. In a mmW system, the UE and the AP may need tofind the best beam pair (e.g., the beam pair with the best transmissionquality and/or the least interference) for transmissions/receptionsbetween the UE and the AP. The transmission and reception ofsynchronization signals and RACH signals may allow the best beam pair tobe identified. In addition, a new reference signal (e.g., a beamreference signal (BRS)) may be used to facilitate the beam searchingtask.

In a wireless backhaul network, APs may need to perform similar tasks toestablish backhaul links with each other. It may be desirable to reusethe access network design and resources as much as possible with minimumdisturbance to the access network performance. In what follows, anexample is provided on how the access network (downlink) synchronizationdesign may be utilized to enable synchronization among APs.

FIG. 5 is a diagram 500 illustrating an example of resource allocationin a mmW system. In the access network, a number of resources may beperiodically allocated for the downlink synchronization. For example,there may be 1 synchronization subframe (e.g., 502) every 5 ms. Duringeach synchronization subframe, all the eNBs (APs) may transmit one ormore of a primary synchronization signal (PSS), an extendedsynchronization signal (ESS), a secondary synchronization signal (SSS),a PBCH, or a BRS. In a mmW system, the signals described above may betransmitted multiple times (e.g., starting with iteration 510 and endingwith iteration 512, with several iterations in between) with differentbeam directions during a synchronization subframe to allow the UEs tofind the best TX/RX beams for communication with the eNBs. In FIG. 5 ,each TX/RX beam directions (e.g., 504, 506, . . . 508) of mmW band isillustrated with a different pattern. For example, during iteration 510,the signals may be transmitted with beam direction 504, and duringiteration 512, the signals may be transmitted with beam direction 506.

In one configuration, an AP may be allowed to stop transmitting during asubset of synchronization resources and instead listen to the incomingsignals and try to synchronize to the AP's neighboring APs, thusovercoming the half-duplex constraint. FIG. 6 is a diagram 600illustrating an example of using a color-code to determine when toswitch from transmitting (e.g., synchronization signals to other APs) tolistening to synchronization signals from each AP. The diagram 600includes a tree 620 illustrating a network of APs and a subframe diagram625 illustrating resource allocation for different subframes. In oneconfiguration, two APs may be assigned two different colors if the twoAPs are directly linked in the tree 620. A subframe in the subframediagram 625 may be assigned a color to indicate that the AP assignedwith the same color may be switching from transmission to listening tosynchronization signals during the subframe.

In the tree 620, each of the APs is assigned one of 3 colors. Each APdecides when to ditch the AP's synchronization transmission based on thecolor assigned to the AP. For example, the AP 602 may be assigned afirst color (illustrated with a first pattern). As a result, the AP 602may switch from transmission to listening to synchronization signalsduring the subframes 610 and 612, which are assigned the first color.Similarly, the AP 604 may be assigned a second color (illustrated with asecond pattern) and may switch from transmission to listening tosynchronization signals during the subframe 614, which is assigned thesecond color. The AP 606 may be assigned a third color (illustrated witha third pattern) and may switch from transmission to listening tosynchronization signals during the subframe 616, which is assigned thethird color.

In one configuration, the available synchronization resources (e.g.,subframes) may be divided into two sets of resources: a first set ofresources and a second set of resources. During the first set ofresources (e.g., the subframes 630), the synchronization transmissionmay follow the downlink synchronization design (e.g., all APs transmitsynchronization signals). During the second set of resources (e.g., thesubframes 610, 612, 614, 616), an AP may be in any of the followingstates for backhaul synchronization: 1) RX mode—synchronizationreception from other APs; 2) TX mode—synchronization transmission with apotentially modified configuration; or 3) hybrid mode—switching betweenRX and TX mode during a single subframe. In one configuration, an AP maybe in any of, or switch between, multiple states (e.g., RX mode, TXmode, hybrid mode) within the second set of resources. For example, in asubset of the second set of resources, the AP may be in RX mode; and inanother subset of the second set of resources, the AP may be in TX mode,and so on.

In one configuration, the downlink synchronization may be reused as muchas possible to reduce the negative effect (e.g., performance reduction)on the UEs. In such a configuration, each AP may modify the AP'ssynchronization transmission configuration in a subset of resources toincrease the backhaul synchronization. For example, the APs may changethe set of beams used for synchronization transmission by changing theelevation angle and/or the azimuth angles. In another example, the APsmay change the signal waveforms or the resources used for thetransmissions (e.g. transmitting synchronization signals in a widerbandwidth). In one configuration, the modified configuration forsynchronization transmission may include any combination of: 1) amodified set of beams to be swept during the synchronizationtransmission (e.g., elevation angle may be modified towards other APs,and/or the set of azimuth angles to be swept may be different from theazimuth angles used for downlink synchronization transmission); 2)modified constituent signals (e.g., PSS/SSS/ESS/PBCH) design andmodified information carried by the constituent signals; or 3) modifiedresources allocated for the transmission (e.g., synchronization signalsmay be transmitted over a wider bandwidth).

In one configuration, each AP in a wireless backhaul network maytransmit some information to inform other APs and UEs about thesynchronization schedule of the AP. For example, an AP may transmit1-bit of information to inform other APs whether the AP is participatingin backhaul synchronization. In case the AP follows a semi-persistentschedule for synchronization TX/RX, the AP may transmit some information(e.g., a few bits of information) from which the schedule can beinferred/identified (e.g. via an index to a preconfigured list ofschedules). In one configuration, the index to a preconfigured list ofschedules may be in the form a hop-count or a color-code. In oneconfiguration, the information from which the schedule can be inferredmay be a random seed used to generate a schedule pattern. In a moredynamic situation, where the AP changes its schedule, the AP maytransmit some information (e.g., a few bits of information) to indicatethe changes to the schedule and specify the future state(s) of the AP.In one configuration, the information to inform other APs and UEs aboutthe synchronization schedule of the AP may be sent in any combination ofMIB, SIB, RRC message.

In one configuration, an AP may decide the schedule of the AP (e.g.,sequence of synchronization states of the AP) based on differentfactors. For example, the schedule of the AP may be determined based onthe information received form all or a subset of neighboring APs. In oneconfiguration, the schedule of the AP may be determined based on therandom seed used by the other APs and/or the hop-count or color-codeused by the other APs. In one configuration, the schedule of the AP maybe determined based on some preconfigured system parameters, and/or somenetwork configuration coming from upper layers, and/or a random seed. Inone configuration, an AP may change the schedule of the AP at any timebased on the information received from all or a subset of other APsand/or some network configurations coming from upper layers.

In one configuration, in order to manage the synchronization schedules,a number of “network configuration nodes” may be defined in the wirelessbackhaul network. The role of the network configuration nodes may be toreceive information from the APs, determine the synchronizationschedules of the APs, and inform the APs about the synchronizationschedules. In one configuration, the APs may report some information tothe network configuration nodes. The reported information from an AP mayinclude measurements and information the AP received from neighboringAPs and UEs. The network configuration nodes may determine thesynchronization schedule for all (or a subset) of APs based on all theinformation the network configuration nodes received and transmit thesynchronization schedule back to the APs. Therefore, APs may determineor modify their synchronization schedule based on the message(s) fromone or more network configuration nodes.

Although the disclosure above focuses on the synchronization aspects ofthe link establishment procedure, similar approach may be applied to theRACH TX/RX process and BRS TX/RX process (e.g., where BRS is not part ofthe synchronization subframe).

FIG. 7 is a flowchart 700 of a method of wireless communication. Themethod may be performed by an mmW base station (e.g., the mmW basestation 180, 310, 452, 454, 456, 458, 460, 602, 604, 606, or theapparatus 902/902′). At 702, the base station may determine a first setof resources to be used for establishing network access for a set ofUEs.

At 704, the base station may determine a second set of resources forestablishing backhaul links with a set of base stations. A resourceschedule of the base station may include the first set of resources andthe second set of resources. In one configuration, the resource schedulemay be determined based on one or more of information received from theset of base stations, a set of preconfigured system parameters, a set ofnetwork configuration received from upper layers, or a random seed.

For example, the resource schedule may be determined based on theinformation received from other base stations to ensure thesynchronization signals from other base stations can be heard. In oneconfiguration, the information received from other base stations mayinclude the color-codes used by the other base stations, and the basestation may select a different color-code in determining the resourceschedule.

The resource schedule may be determined based on some preconfiguredsystem parameters. For example, the base station may be initiallyconfigured to stop transmitting synchronization signal on a set ofresources. In one configuration, the set of resources may bepreconfigured. In one configuration, the set of resources may depend inpart on the cell ID of the base station.

In one configuration, the upper layers of the base station may determinethe resource schedule. For example, the resource schedule may bedetermined based on some measurements of the state of the base stationperformed by the upper layers. Similarly, the resource schedule may bedetermined based on a random seed.

In one configuration, the first set of resources may be a first set ofsynchronization resources and the second set of resources may be asecond set of synchronization resources. The base station may transmitsynchronization signals during each of the first set of synchronizationresources. In one configuration, during the second set ofsynchronization resources, the base station may perform one or more ofreceiving synchronization signals, switching between receiving andsending synchronization signals during a resource of the second set ofsynchronization resources, or sending synchronization signal with amodified configuration. In one configuration, the modified configurationmay include one or more of a modified set of beams to be swept duringsynchronization transmission, a modified design of constituent signalsand information carried by the constituent signals, or modifiedresources allocated for the synchronization transmission. In oneconfiguration, the modified set of beams may include one or more of amodified elevation angle or a modified set of azimuth angles to beswept. In one configuration, the constituent signals may include one ormore of PSS, SSS, ESS, or PBCH. In one configuration, the modifiedresources may include a wider bandwidth than a bandwidth fortransmitting synchronization signals to the set of UEs.

In one configuration, the first set of resources may be a first set ofRACH resources and the second set of resources may be a second set ofRACH resources. The base station may receive RACH preamble during eachof the first set of RACH resources. In one configuration, during thesecond set of RACH resources, the base station may perform one or moreof sending RACH preamble, switching between receiving and sending RACHpreamble during a resource of the second set of RACH resources, orsending and/or receiving RACH preamble with a modified configuration. Inone configuration, the modified configuration may include one or more ofa modified set of beams to be swept during RACH transmission/receptionor modified resources allocated for the RACH transmission/reception. Inone configuration, the modified set of beams may include one or more ofa modified elevation angle or a modified set of azimuth angles to beswept. In one configuration, the modified resources may include a widerbandwidth than a bandwidth for transmitting RACH preamble by the set ofUEs

In one configuration, the first set of resources may be a first set ofbeam reference signal (BRS) resources and the second set of resourcesmay be a second set of BRS resources. In one configuration, the basestation may transmit BRS during each of the first set of BRS resources.In one configuration, during the second set of BRS resources, the basestation may perform one or more of receiving BRS, switching betweenreceiving and sending BRS during a resource of the second set of BRSresources, or sending BRS with a modified configuration. In oneconfiguration, the modified configuration may include one or more of amodified set of beams to be swept during BRS transmission or modifiedresources allocated for the BRS transmission. In one configuration, themodified set of beams may include one or more of a modified elevationangle or a modified set of azimuth angles to be swept. In oneconfiguration, the modified resources may include a wider bandwidth thana bandwidth for transmitting BRS to the set of UEs.

At 706, the base station may optionally transmit information regardingthe resource schedule. In one configuration, the information regardingthe resource schedule may include one or more of a single bit toindicate that the base station participates in a backhaul network, afirst set of bits to indicate the resource schedule, or a second set ofbits to indicate changes in the resource schedule and a future state ofthe resource schedule. In one configuration, the first set of bits mayinclude a random seed or an index to a preconfigured list of resourceschedules. In one configuration, the index may include a hop-count or acolor-code. In one configuration, the information regarding the resourceschedule may be carried in one or more of a MIB, a SIB, or a RRCmessage.

At 708, the base station may optionally change the resource schedulebased on at least one of information received from the set of basestations or a set of network configuration received from upper layers.

FIG. 8 is a flowchart 800 of a method of wireless communication. Themethod may be performed by a network configuration node. In oneconfiguration, the network configuration node may be an mmW base station(e.g., the mmW base station 180, 310, 452, 454, 456, 458, 460, 602, 604,606, or the apparatus 902/902′). In one configuration, the networkconfiguration node may be a first base station. At 802, the first basestation may receive a set of reports from a set of base stations. In oneconfiguration, a report of the set of reports received from a third basestation within the set of base stations may include one or more of asingle bit to indicate that the third base station participates in abackhaul network, a first set of bits to indicate a resource schedule ofthe third base station, or a second set of bits to indicate changes inthe resource schedule of the third base station and a future state ofthe resource schedule of the third base station. In one configuration, areport of the set of reports received from a third base station withinthe set of base stations may include measurements and information thethird base station received from neighboring base stations and UEs.

At 804, the first base station may determine a resource schedule for asecond base station within the set of base stations based on the set ofreports. In one configuration, the resource schedule may be furtherdetermined based on one or more of a set of preconfigured systemparameters, a set of network configuration received from upper layers,or a random seed.

For example, the resource schedule may be determined based on the set ofreports to ensure the synchronization signals from other base stationscan be heard by the second base station. In one configuration, the setof reports may include the color-codes used by the other base stations,and the first base station may select a different color-code indetermining the resource schedule for the second base station.

The resource schedule may be determined based on some preconfiguredsystem parameters. For example, the second base station may be initiallyconfigured to stop transmitting synchronization signal on a set ofresources. In one configuration, the set of resources may bepreconfigured. In one configuration, the set of resources may depend inpart on the cell ID of the second base station.

In one configuration, the upper layers may determine the resourceschedule. For example, the resource schedule may be determined based onsome measurements of the state of the second base station performed bythe upper layers. Similarly, the resource schedule may be determinedbased on a random seed.

The first base station may potentially have more information about thesystem through receiving reports from multiple base stations. The firststation may process the set of reports and come up with a resourceschedule for each of the set of base stations to allow efficientutilization of the resources in the system while providing goodperformance for the UEs and base stations. For example, the first basestation may select different random seeds for the set of base stationsto assure the set of base stations can hear each other's synchronizationtransmission.

In one configuration, the resource schedule may include a first set ofresources to be used for establishing network access for a set of UEsvia the second base station and a second set of resources forestablishing backhaul links for the second base station. In oneconfiguration, the first set of resources may be a first set ofsynchronization resources and the second set of resources may be asecond set of synchronization resources. In one configuration, the firstset of resources may be a first set of RACH resources and the second setof resources may be a second set of RACH resources. In oneconfiguration, the first set of resources may be a first set of BRSresources and the second set of resources may be a second set of BRSresources.

At 806, the first base station may transmit the resource schedule to thesecond base station. The second base station may perform synchronizationbased on the resource schedule.

FIG. 9 is a conceptual data flow diagram 900 illustrating the data flowbetween different means/components in an exemplary apparatus 902. Theapparatus may be an eNB. The apparatus 902 may include a receptioncomponent 904 that receives information from a base station 950. In oneconfiguration, the reception component 904 may perform operationsdescribed above with reference to 802 in FIG. 8 .

The apparatus 902 may include a transmission component 910 thattransmits resource schedule or information regarding resource scheduleto the base station 950. In one configuration, the transmissioncomponent 910 may perform operations described above with reference to706 in FIG. 7 or 806 in FIG. 8 . The reception component 904 and thetransmission component 910 may cooperate to coordinate the communicationof the apparatus 902.

The apparatus 902 may include a resource scheduling component 906 thatdetermines resource schedule based on information received from thereception component 904 and send the determined resource schedule orinformation regarding the determined resource schedule to thetransmission component 910. In one configuration, the resourcescheduling component 906 may perform operations described above withreference to 702, 704, or 708 in FIG. 7 , or 804 in FIG. 8 .

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 7 and8 . As such, each block in the aforementioned flowcharts of FIGS. 7 and8 may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

FIG. 10 is a diagram 1000 illustrating an example of a hardwareimplementation for an apparatus 902′ employing a processing system 1014.The processing system 1014 may be implemented with a bus architecture,represented generally by the bus 1024. The bus 1024 may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system 1014 and the overall designconstraints. The bus 1024 links together various circuits including oneor more processors and/or hardware components, represented by theprocessor 1004, the components 904, 906, 910, and the computer-readablemedium/memory 1006. The bus 1024 may also link various other circuitssuch as timing sources, peripherals, voltage regulators, and powermanagement circuits, which are well known in the art, and therefore,will not be described any further.

The processing system 1014 may be coupled to a transceiver 1010. Thetransceiver 1010 is coupled to one or more antennas 1020. Thetransceiver 1010 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1010 receives asignal from the one or more antennas 1020, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1014, specifically the reception component 904. Inaddition, the transceiver 1010 receives information from the processingsystem 1014, specifically the transmission component 910, and based onthe received information, generates a signal to be applied to the one ormore antennas 1020. The processing system 1014 includes a processor 1004coupled to a computer-readable medium/memory 1006. The processor 1004 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1006. The software, whenexecuted by the processor 1004, causes the processing system 1014 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1006 may also be used forstoring data that is manipulated by the processor 1004 when executingsoftware. The processing system 1014 further includes at least one ofthe components 904, 906, 910. The components may be software componentsrunning in the processor 1004, resident/stored in the computer readablemedium/memory 1006, one or more hardware components coupled to theprocessor 1004, or some combination thereof. The processing system 1014may be a component of the eNB 310 and may include the memory 376 and/orat least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375.

In one configuration, the apparatus 902/902′ for wireless communicationmay include means for determining a first set of resources to be usedfor establishing network access for a set of UEs. In one configuration,the means for determining a first set of resources may performoperations described above with regard to 702 in FIG. 7 . In oneconfiguration, the means for determining a first set of resources mayinclude the resource scheduling component 906 and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means fordetermining a second set of resources for establishing backhaul linkswith a set of base stations. In one configuration, the means fordetermining a second set of resources may perform operations describedabove with regard to 704 in FIG. 7 . In one configuration, the means fordetermining a second set of resources may include the resourcescheduling component 906 and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means fortransmitting information regarding the resource schedule. In oneconfiguration, the means for transmitting information regarding theresource schedule may perform operations described above with regard to706 in FIG. 7 . In one configuration, the means for transmittinginformation regarding the resource schedule may include the transceiver1010, the one or more antennas 1020, the transmission component 910,and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means forchanging the resource schedule based on at least one of informationreceived from the set of base stations or a set of network configurationreceived from upper layers. In one configuration, the means for changingthe resource schedule may perform operations described above with regardto 708 in FIG. 7 . In one configuration, the means for changing theresource schedule may include the resource scheduling component 906and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means forreceiving a set of reports from a set of base stations. In oneconfiguration, the means for receiving a set of reports may performoperations described above with regard to 802 in FIG. 8 . In oneconfiguration, the means for receiving a set of reports may include thetransceiver 1010, the one or more antennas 1020, the reception component904, and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means fordetermining a resource schedule for a second base station within the setof base stations based on the set of reports. In one configuration, themeans for determining a resource schedule for a second base station mayperform operations described above with regard to 804 in FIG. 8 . In oneconfiguration, the means for determining a resource schedule for asecond base station may include the resource scheduling component 906and/or the processor 1004.

In one configuration, the apparatus 902/902′ may include means fortransmitting the resource schedule to the second base station. In oneconfiguration, the means for transmitting the resource schedule to thesecond base station may perform operations described above with regardto 806 in FIG. 8 . In one configuration, the means for transmitting theresource schedule to the second base station may include the transceiver1010, the one or more antennas 1020, the transmission component 910,and/or the processor 1004.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 902 and/or the processing system 1014 of theapparatus 902′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1014 mayinclude the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication of a firstnetwork node, comprising: receiving a set of reports from a set of oneor more network nodes; determining a resource schedule for a secondnetwork node within the set of one or more network nodes based on theset of reports, wherein the resource schedule comprises a first set ofresources to be used for establishing network access for a set of userequipments (UEs) via the second network node and a second set ofresources for establishing backhaul links for the second network node,wherein the first set of resources is a first set of synchronizationresources and the second set of resources is a second set ofsynchronization resources, wherein a report of the set of reportsreceived from a third network node within the set of one or more networknodes comprises one or more of a first indication that the third networknode participates in a backhaul network, or a second indication ofchanges in a resource schedule of the third network node and a futurestate of the resource schedule of the third network node; andtransmitting the resource schedule to the second network node.
 2. Themethod of claim 1, wherein the report of the set of reports receivedfrom the third network node within the set of one or more network nodescomprises measurements and information the third network node receivedfrom neighboring network nodes and UEs.
 3. The method of claim 1,wherein the resource schedule is further determined based on one or moreof a set of preconfigured system parameters, a set of networkconfiguration received from upper layers, or a random seed.
 4. Themethod of claim 1, wherein the report of the set of reports receivedfrom the third network node within the set of one or more network nodescomprises a third indication of the resource schedule of the thirdnetwork node.
 5. An apparatus for wireless communication, the apparatusbeing a first network node, comprising: a memory; and at least oneprocessor coupled to the memory and configured to: receive a set ofreports from a set of one or more network nodes; determine a resourceschedule for a second network node within the set of one or more networknodes based on the set of reports, wherein the resource schedulecomprises a first set of resources to be used to establish networkaccess for a set of user equipments (UEs) via the second network nodeand a second set of resources to establish backhaul links for the secondnetwork node, wherein the first set of resources is a first set ofsynchronization resources and the second set of resources is a secondset of synchronization resources, wherein a report of the set of reportsreceived from a third network node within the set of one or more networknodes comprises one or more of a first indication that the third networknode participates in a backhaul network, or a second indication ofchanges in a resource schedule of the third network node and a futurestate of the resource schedule of the third network node; and transmitthe resource schedule to the second network node.
 6. The apparatus ofclaim 5, wherein the report of the set of reports received from thethird network node within the set of one or more network nodes comprisesmeasurements and information the third network node received fromneighboring network nodes and UEs.
 7. The apparatus of claim 5, whereinthe resource schedule is further determined based on one or more of aset of preconfigured system parameters, a set of network configurationreceived from upper layers, or a random seed.
 8. The apparatus of claim5, wherein the report of the set of reports received from the thirdnetwork node within the set of one or more network nodes comprises athird indication of the resource schedule of the third network node. 9.An apparatus for wireless communication, the apparatus being a firstnetwork node, comprising: means for receiving a set of reports from aset of one or more network nodes; means for determining a resourceschedule for a second network node within the set of one or more networknodes based on the set of reports, wherein the resource schedulecomprises a first set of resources to be used to establish networkaccess for a set of user equipments (UEs) via the second network nodeand a second set of resources to establish backhaul links for the secondnetwork node, wherein the first set of resources is a first set ofsynchronization resources and the second set of resources is a secondset of synchronization resources, wherein a report of the set of reportsreceived from a third network node within the set of one or more networknodes comprises one or more of a first indication that the third networknode participates in a backhaul network, or a second indication ofchanges in a resource schedule of the third network node and a futurestate of the resource schedule of the third network node; and means fortransmitting the resource schedule to the second network node.
 10. Theapparatus of claim 9, wherein the report of the set of reports receivedfrom the third network node within the set of one or more network nodescomprises measurements and information the third network node receivedfrom neighboring network nodes and UEs.
 11. The apparatus of claim 9,wherein the resource schedule is further determined based on one or moreof a set of preconfigured system parameters, a set of networkconfiguration received from upper layers, or a random seed.
 12. Theapparatus of claim 9, wherein the report of the set of reports receivedfrom the third network node within the set of one or more network nodescomprises a third indication of the resource schedule of the thirdnetwork node.
 13. A non-transitory computer-readable medium storingcomputer executable code, the code when executed by a processor causethe processor to: receive a set of reports from a set of one or morenetwork nodes; determine a resource schedule for a second network nodewithin the set of one or more network nodes based on the set of reports,wherein the resource schedule comprises a first set of resources to beused to establish network access for a set of user equipments (UEs) viathe second network node and a second set of resources to establishbackhaul links for the second network node, wherein the first set ofresources is a first set of synchronization resources and the second setof resources is a second set of synchronization resources, wherein areport of the set of reports received from a third network node withinthe set of one or more network nodes comprises one or more of a firstindication that the third network node participates in a backhaulnetwork, or a second indication of changes in a resource schedule of thethird network node and a future state of the resource schedule of thethird network node; and transmit the resource schedule to the secondnetwork node.
 14. The non-transitory computer-readable medium of claim13, wherein the report of the set of reports received from the thirdnetwork node within the set of one or more network nodes comprisesmeasurements and information the third network node received fromneighboring base stations and UEs.
 15. The non-transitorycomputer-readable medium of claim 13, wherein the resource schedule isfurther determined based on one or more of a set of preconfigured systemparameters, a set of network configuration received from upper layers,or a random seed.
 16. The non-transitory computer-readable medium ofclaim 13, wherein the report of the set of reports received from thethird network node within the set of one or more network nodes comprisesa third indication of the resource schedule of the third network node.